PROTECTION CICUIT
5/8
NOTE
1.
OVER CURRENT PROTECTION
–
There are 7 digital amp ICs (IC 251/351/851/261/361/451/461) for 7 channel audio
amplification. Pin 5 of these ICs outputs a LOW state when the final output over
current is detected. Pin 5 is connected to base of 7 transistors
(Q251/351/851/261/361/451/461) respectively.
–
These 7 transistors are PNP type, and are turned on when base voltage goes LOW.
–
Any one of these 7 transistors turned on (when over current occurs) would turn off
Q281, then turn on Q286 and Q282. The emitter of Q282 becomes 0 volts, and the
LOW state would be sent to pin 31 of IC501 through R290 triggering the protection.
•
2. DC (to speaker) DETECT PROTECTION
–
There are 7 resistors connected to 7 channel speaker outputs (just after low pass
filter). The other side of these resistors are tied together and connected to the base
of Q284 and Q285.
–
If a DC voltage occurs at any audio speaker output line, a (+) will turn on Q285 or a(-)
turns on Q284 and Q283.
–
A LOW occurs at collector of Q285 when Q285 or Q283 are turned on. The LOW
state is sent to pin 31 of IC501 through R289 and triggers the protect function.
•
3. AC DETECT PROTECTION
–
The AC power from winding S1 of the power transformer is rectified by D1171,
producing a negative DC voltage which is applied through R1171 and R1172 to base
of Q1174, keeping it cut off, and keeping the collector HIGH (5v).
–
When the AC power (S1) disappears, +0.7v is applied to the base of Q1174, turning it
on into saturation. A LOW is sent to IC501 pin 31 through R1178 triggering the
protect function.
Summary of Contents for RX-D201
Page 5: ...POWER SUPPLY BLOCK DIAGRAM AMP_ B switch regulator ...
Page 11: ...Tip to measure the outputs of Q1101 1102 POWER SUPPLY 3 5 ...
Page 45: ...PROTECTION CICUIT 8 8 4 39V 0 02V ...
Page 57: ...QUICK CHECK TABLE 1 2 ...
Page 58: ...QUICK CHECK TABLE 2 2 SHORT OR OPEN ...
Page 67: ...DIGITAL AMPLIFIER 4 8 Problems of a digital Amplifier ...
Page 68: ...DIGITAL AMPLIFIER 5 8 solving the problem 1 D1 A2 A1 D2 ...
Page 70: ...DIGITAL AMPLIFIER 8 8 solving the problem 3 Three features ...
Page 71: ...DIGITAL AMPLIFIER 8 8A solving the problem 3 Feature 1 ...
Page 74: ...DIGITAL AMPLIFIER 8 8C solving the problem 3 Feature 3 ...
Page 75: ...DIGITAL AMPLIFIER 3 8 Block Diagram for RX D Series ...
Page 80: ...AUDIO DIGITAL PROCESS 1 8 ...
Page 85: ...AUDIO DIGITAL PROCESS 6 8 CC Converter 2 Range Expansion ...
Page 87: ...Audio Input output Path USB To ...
Page 88: ...Audio Input Process Path IC681 IC610 IC661 IC620 IC685 IC686 IC630 IC671 RX D401 402 701 702 ...
Page 92: ...VIDEO PROCESS HDMI2 7 Video Connection for RX D401 D402 HDMI AUDIO HDMI VIDEO IC771 IC781 ...
Page 93: ...VIDEO PROCESS HDMI3 7 Video Connection for RX D701 D702 HDMI AUDIO HDMI VIDEO IC771 IC781 ...
Page 99: ...USB WIRE OR WIRELESS1 5 All of RX D series equipped wire USB feature ...
Page 104: ...Thank you ...